JimT

I was at an auto shop recently where the owner of a 57 chevy was having a front end alignment performed on his car. The engine had been upgraded to a 350, and while we were discussing his car/engine, the owner asked me if I could tell if it was a 2bolt or 4bolt main. The tech, hearing our discussion walked to the front of the car, looked at the block, and stated it was a 4bolt main. I asked how he knew and he stated there is an extra plug on the front of the engine.
I know about 350 block casting numbers, and the most obvious method of dropping the pan, etc, but can you determine main bearing info by some external engine block configuration?

Gordonm

BS. I hope you don't let him work on your car.

L88Plus

Unless he built the engine, the tech is full of it.
But he has a 50% chance of being right and wrong.
Just 'cause I think he's full of it, I'll say it's a 2-bolt block even though I've never seen it.
I have the same chance of being right as the tech.
Can't tell without pulling the pan except for one or two short deck big block exceptions.

billla

:BS x2

There's no way to tell from the outside, period. There are some rules of thumb that might be worth a bet (truck blocks are usually 4-bolt, etc.) but there is no way to be sure absent dripping the pan.

I too would have a tendency to avoid the tech...as anyone that's built a GEN I SBC has been through this question

tnovot

Actually the tech might be on to something. I remember reading somewhere that a 4 bolt can usually be identified by the small 3/8"? pipe plug right above and slightly to the passenger side of the timing cover if the plug has a square head. Maybe this is just an old wives tale but it has been true for the last 2 engines I worked on. Even if it isn't true, the tech may think it is and that wouldn't necesarily make him incompetent in his own area of expertise.
Terry

Lee H

BS layers like that can run a scam that will cost you dearly. Run Forest Run!

Mike Ward

I believe the plug on the front was unique to engines built at Tonawanda. This plant built the majority of GM truck and commercial engines, many of which were 4 bolt.

The plug by itself is meaningless.

Easy Mike

I thought Flint used the plugs, but I agree, the plug won't tell you whether it's 2 or 4 bolt.

GrandSportC3

I think that there are 2 ways to tell.. Some casting numbers only came with 4 bolts and some only came with 2 bolts. Some of them came with both.. If it's a casting number that came in 2 or 4 bolt, you need to pull the pan to know for sure.

thatcorvetteguy

X2

Korevette

As young kids we used to scour the wrecking yards looking for humping camels or was that camel hump cylinder heads, four bolt mains, Z-28 aluminum intakes, rams horn manifolds etc, etc.

We worked from the advice of others in thier search for the elusive LT1 that got away. Big harmonic balancers, code casting on the left rear side of the block, forged Z-28 pistons, wide forged parting lines or simple parting lines on crank shafts meant something, lets don't even start on the old 'Power Pak' heads that you could not even roll a pea done the intake side.

I fondly remember those days. My best insurance as already stated was a minimal tear down such as pan and heads to measure what I had.

Ah ya those good old days of chasing dreams...

Dano,

billla

...and there were always just enough finds to make it worthwhile.

Hasn't changed, really - LQ9s, Vortecs...just different casting numbers.

You kids just run along and let us old farts remember

AllC34Me

...and if only we old farts could find those locations again and then have the energy and the strength to root around in them...now that would be a fun day...locate it and they will come.
Even us old farts.
David

Al Davis

I have a 79 010 original numbers matching engine. Don't know what it is, I decided to pull the original engine even if it was a 2 or 4 bolt and store it. I purchased a 010 78 truck block w/ 4 bolt caps for $125.00 he had it in his garage for 15 years. I will build it into a 383 450hp with all new parts over the winter.